Lost Odyssey gave me the same exact problem. I figured out the issue though.
I am using optical audio cable for surround sound and the area on the 360 video/audio cable that allows you to plug it in seems to be the issue here. It doesn't seem to want to hold onto the cable properly and it moves around.
I switch it between the PS3 and the 360 depending on which console I am using at the moment. A little tape and now all is fine.
@Zen
If Fable II was the issue, damn right I would go right back and demand a new one!! I already love this game, it is so much like Fable I, and that is a good thing. Not crazy about the dog though, he is making searching way too easy.
iPhone = Great gaming device. Don't agree? Who cares, because you're wrong.
Currently playing:
Final Fantasy VI (iOS), Final Fantasy: Record Keeper (iOS) & Dragon Quest V (iOS)